"DECKED" ENGINE
Racer
Joined: Nov 2000
Posts: 317
Likes: 1
From: East China MI.
Re: "DECKED" ENGINE (64BB)
64BB,
Im sure Duke and Clem as well as others will jump in with more reasons,but two come to mind.
NO.1,engines get decked for true compression.Compression is almost always slightly lower than advertised,and drag racers often want all the compression they can get within the rules.
NO.2,deck surfaces get warped for a number of different reasons and need to be flat for good sealing of water jackets and combustion chambers.
Hope this helps..............Bill S
Im sure Duke and Clem as well as others will jump in with more reasons,but two come to mind.
NO.1,engines get decked for true compression.Compression is almost always slightly lower than advertised,and drag racers often want all the compression they can get within the rules.
NO.2,deck surfaces get warped for a number of different reasons and need to be flat for good sealing of water jackets and combustion chambers.
Hope this helps..............Bill S
Race Director
Joined: May 2000
Posts: 12,712
Likes: 2,264
Re: "DECKED" ENGINE (olredalert)
That about covers it, but I should add that machine shops typically want to take a cut just to insure that the deck is level and parallel to the crankshaft, however, contrary to popular myth, the deck is usually parallel. The block machining transfer lines were quite accurate.
The trouble with decking is that is removes the stamped numbers that can prove you have a correct original engine, so you should avoid decking unless the deck really isn't parallel to the crank based on careful measurements. You can also measure for flatness and modern composition gaskets will handle about .003" warp without problems.
Duke
The trouble with decking is that is removes the stamped numbers that can prove you have a correct original engine, so you should avoid decking unless the deck really isn't parallel to the crank based on careful measurements. You can also measure for flatness and modern composition gaskets will handle about .003" warp without problems.
Duke
Le Mans Master
Joined: Mar 1999
Posts: 6,744
Likes: 1
From: delmont pa
Cruise-In I Veteran
Cruise-In II Veteran
Re: "DECKED" ENGINE (SWCDuke)
i have found that most blocks are .004 to .006 off of being paralel to the crank center line, but to get the deck clearance correct sometimes takes .010 to .012 cut. always deck a block before you bore it if the shop uses a boring bar the clamps the the deck surface because the boring bar will bore perpendicular to the deck but will not be perpendicular to the crank center line. :chevy
Team Owner
Joined: Oct 2000
Posts: 38,897
Likes: 1,922
From: Washington Michigan
Re: "DECKED" ENGINE (clem zahrobsky)
It's almost impossible to "deck" a block without taking out the numbers on the stamp pad. "Decking" is done in a machine with a rotary cutting wheel 18"-24" in diameter; in order to machine the entire deck sealing surface flat, the rotary cutter has to take out the stamp pad surface too.
Safety Car
Joined: Feb 2000
Posts: 4,977
Likes: 38
From: Massachusetts , USA,
Re: "DECKED" ENGINE (JohnZ)
The block on my 1966 427, now 433, was decked when it was rebuilt, by previous owner in 1994, enough to wipe out engine pad numbers completly, as it is a vintage 1966 block .... has survived many years of use ....who has any idea how many times it has had engine work.....the sad part is the previous owner had it restamped, I would have left the pad blank...anyways have all the paperwork on rebuild & no idea how much taken off............but when I put on Alum heads noted the pistons are .005" down in the hole...if a block has been in use for 32 years , decking is necessary to true things up & do a quality rebuild .... if you do mill heads, check the distrbutor length & use spacers so that things dont bind , this was a problem i had initially before , figured things out....babling of the old dog WOOF WOOOOF. :) :flag :seeya
[Modified by StrayDog, 10:46 AM 4/27/2002]
[Modified by StrayDog, 10:46 AM 4/27/2002]
Intermediate
Joined: Apr 2002
Posts: 30
Likes: 3
Re: "DECKED" ENGINE (64BB)
Modern casting techniques eliminate many internal stresses within an engine block. However, the remaing internal stresses can distort sections of the block. Now, assume you are a machine shop that is going to rebuild an engine and guarantee that rebuild for 50,000 miles or more. You are going to clean the block thoroughly inside and out, then place the block in a fixture and skim the head mounting surfaces to make sure they are straight and true. The heads are going to be trued as well, because you do not want a failed head gasket to ruin your otherwise perfectly rebuilt engine.
It's that simple- making the rebuild last through the warranty period.
-Noland Adams
It's that simple- making the rebuild last through the warranty period.
-Noland Adams
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